
/* Copyright 1998 by the Massachusetts Institute of Technology.
 *
 * Permission to use, copy, modify, and distribute this
 * software and its documentation for any purpose and without
 * fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting
 * documentation, and that the name of M.I.T. not be used in
 * advertising or publicity pertaining to distribution of the
 * software without specific, written prior permission.
 * M.I.T. makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 */

#include "ares_setup.h"

#include "ares.h"
#include "ares_nowarn.h"
#include "ares_private.h"

/* This is an internal function.  Its contract is to read a line from
 * a file into a dynamically allocated buffer, zeroing the trailing
 * newline if there is one.  The calling routine may call
 * ares__read_line multiple times with the same buf and bufsize
 * pointers; *buf will be reallocated and *bufsize adjusted as
 * appropriate.  The initial value of *buf should be NULL.  After the
 * calling routine is done reading lines, it should free *buf.
 */
int ares__read_line(FILE* fp, char** buf, size_t* bufsize)
{
    char* newbuf;
    size_t offset = 0;
    size_t len;

    if (*buf == NULL) {
        *buf = ares_malloc(128);
        if (!*buf)
            return ARES_ENOMEM;
        *bufsize = 128;
    }

    for (;;) {
        int bytestoread = aresx_uztosi(*bufsize - offset);

        if (!fgets(*buf + offset, bytestoread, fp))
            return (offset != 0) ? 0 : (ferror(fp)) ? ARES_EFILE : ARES_EOF;
        len = offset + strlen(*buf + offset);
        if ((*buf)[len - 1] == '\n') {
            (*buf)[len - 1] = 0;
            break;
        }
        offset = len;
        if (len < *bufsize - 1)
            continue;

        /* Allocate more space. */
        newbuf = ares_realloc(*buf, *bufsize * 2);
        if (!newbuf) {
            ares_free(*buf);
            *buf = NULL;
            return ARES_ENOMEM;
        }
        *buf = newbuf;
        *bufsize *= 2;
    }
    return ARES_SUCCESS;
}
